SAN FRANCISCO— The Center for Biological Diversity filed a formal notice of intent today to sue the U.S. Environmental Protection Agency for failing to enforce Clean Air Act standards limiting dangerous pollution from tiny airborne particles like soot. The legal action was taken in response to the agency’s repeated failure to ensure that nine states are implementing legally required plans to meet standards to reduce soot pollution.

“The Clean Air Act can only work to protect public health and ecosystems if it is actually enforced,” said Jonathan Evans, toxics and endangered species campaign director at the Center. “EPA and the states have a moral and legal duty to work to together to clean up the toxic soot that’s polluting our skies.”

Soot, referred to as “particulate matter” by the EPA, is known to cause a range of health problems for people and wildlife. It fills the air with haze, harms plant life and acidifies water bodies. Particulate matter made up of tiny particles, about 30 times smaller than the width of the average human hair, can lodge deep in the lungs, posing serious health risks to humans and wildlife.

A range of toxic soot has been associated with a broad spectrum of harms to terrestrial and aquatic ecosystems, including decreased biodiversity. This widespread pollution also causes regional haze that fouls vistas in scenic cities, national parks and wilderness areas.

The Clean Air Act requires the EPA to set nationwide, health-based standards for particulate pollution and sets mandatory deadlines for the states to develop, and for the agency to approve, specific plans for meeting the standards. In communities throughout Alaska, Arizona, California, Michigan, Ohio, Pennsylvania, Wisconsin, South Carolina and Tennessee, the EPA has failed to rule on whether metropolitan areas have submitted adequate plans to reduce soot pollution. The Center’s notice letter demands that the agency correct these violations in order to set up plans to reduce dangerous soot levels.

“The science is clear. Soot poisons our skies, our bodies and our ecosystems,” said Evans. “The EPA needs to take steps right now to implement the Clean Air Act to save lives and protect our environment.”

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 625,000 members and online activists dedicated to the protection of endangered species and wild places.